1. Technical Field
The present invention relates to a spectral image acquisition apparatus and a light reception wavelength acquisition method employed in the spectral image acquisition apparatus.
2. Related Art
In general, apparatuses which receive incident light by Fabry-Perot etalon (an interference filter) having a pair of reflection films which face each other, perform plane spectroscopy using the interference filter on light having a wavelength based on a dimension of a gap between the reflection films, and perform imaging using a camera have been used (refer to JP-A-4-125429, for example).
The apparatus disclosed in JP-A-4-125429 may change a wavelength of light to be subjected to plane spectroscopy by changing an inclination angle of the interference filter having the reflection films facing each other and perform imaging using the light having the wavelength which has been subjected to the plane spectroscopy so as to obtain a spectral image.
The interference filter changes a wavelength of transmission light in accordance with the dimension of the gap between the reflection films. However, it is difficult to uniformly form the dimension of the gap between the reflection films in fabrication of the interference filter, and therefore, in-plane variation occurs in the dimension of the gap between the reflection films due to a fabrication error or the like in practice. Such in-plane variation is not taken into consideration in JP-A-4-125429, and therefore, light transmitted through the interference filter has different transmission wavelengths in different portions, that is, wavelengths of light beams obtained by the plane spectroscopy are not uniform (or in-plane unevenness occurs).
When such in-plane unevenness occurs, light beams having different wavelengths are received by light receiving elements included in the camera, and accordingly, a spectral image having a target wavelength may not be obtained with high accuracy.